It has recently been discovered that surgical lesions to the anterior hippocampus, or lesions of the septal-diagonal band area, both of which partially denervate the remaining hippocampal formation, cause an extensive anomalous sympathetic innervation of the hippocampal tissue caudal to the lesion (Loy & Moore, 1977; Stenevi & Bjorklund, 1978). This innervation comes from axons whose cell bodies lie in the superior cervical ganglia. The anomalous innervation can be eliminated by removal of these ganglia prior to performing the brain lesion. The possible functional significance of this anomalous innervation is unknown. The primary objective of the proposed research is to observe and analyze the behavior of rats with anterior hippocampal lesions, in which this growth is present, and compare their behavior with that of rats with similar brain damage, but without the anomalous innervation. These latter animals will have the anomalous innervation prevented by superior cervical ganglionectomy. We will examine the behavior of these animals, together with appropriate controls, in several test situations which have previously proved to be sensitive to the effects of hippocampal damage, namely: spontaneous alternation, open field exploration, spatial mazes (Hebb-Williams and Olton-Samuelson), and the acquisition, reversal and extinction of a brightness discrimination. The anomalous innervation will be examined using histofluorescence procedures, and some of the brains with anomalous innervation will be examined with electron microscope techniques.